How does the signal "Analyzer Element" work to get CM and DM for EMI simulation

Albert_Dunford

PSIM has the ability to do EMC simulations and we provide a LISN and Signal Analyzer element. The LISN element measures the common mode and differential mode currents but it does not measure them directly we need to do a bit of math to separate them which is what the signal analyzer does

 

 

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Albert_Dunford

What is the underlying math? Well the LISN is providing a measurement path for Icm and Idm which is measured producing VL and VN. Then we just add and subtract. To get the CM and DM components

 

The signal analyzer is doing the math.

The impedance network of the LISN changes depending on the standard you are complying with, this is why the measurement circuit is represented with simple impedance blocks.